Orthopaedic Surgery - Hip Replacement

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Basics

Total hip arthroplasty, commonly called hip replacement, is a reconstructive procedure used to treat advanced destruction of the hip joint.

Many forms of arthritis and other hip disorders can lead to progressive loss of articular cartilage, resulting in pain, stiffness, impaired walking, and loss of function.

When symptoms become severe and nonoperative treatment no longer provides adequate relief, the damaged joint can be replaced surgically with prosthetic components.

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Age Considerations

Hip replacement is most commonly performed in older adults, although it is increasingly used in younger patients when symptoms are severe.

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Older Patients

Older patients may have a greater burden of medical comorbidity and may therefore have increased perioperative risk from conditions such as:

Cardiovascular disease, pulmonary disease, renal dysfunction, frailty, or osteoporosis.

Preoperative medical optimization is especially important in this population.

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Younger Patients

Patients younger than approximately 50 years have a higher lifetime probability of requiring revision surgery because their expected lifespan may exceed the longevity of the prosthesis.

Their generally higher activity levels may also increase cumulative implant wear.

For this reason, joint-preserving or other alternative strategies should be considered when appropriate.

These may include:

Continued medical management, corrective osteotomy, selected hip-preserving procedures, or, rarely, hip arthrodesis.

Nevertheless, age alone is not an absolute contraindication to total hip arthroplasty when arthritis is severe and disabling.

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Implant Fixation

Hip components may be secured to bone with either:

Cemented fixation or uncemented biologic fixation.

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Cemented Fixation

Bone cement provides immediate mechanical fixation between the implant and bone.

It remains useful in selected patients, particularly those with poor bone quality or certain fracture patterns.

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Uncemented Fixation

Uncemented components have porous or roughened surfaces that permit bone ongrowth or ingrowth.

Over time, biologic fixation develops as host bone integrates with the implant surface.

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Prevention and Delay of Surgery

Progression to hip replacement cannot always be prevented.

However, symptoms and joint loading may sometimes be reduced by:

Weight reduction, low-impact exercise, activity modification, physical therapy, and appropriate treatment of the underlying hip disorder.

These measures may postpone surgery in selected patients.

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Epidemiology

Most hip replacements have historically been performed in patients older than 65 years, although the procedure is now increasingly common in younger adults.

The overall number of total hip arthroplasties continues to increase because of population aging, expanding indications, and favorable long-term outcomes.

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Risk Factors for Hip Disease Requiring Replacement

The risk factors depend on the underlying diagnosis.

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Primary Osteoarthritis

Factors associated with hip osteoarthritis include:

Age, obesity, abnormal hip morphology, previous trauma, and high cumulative mechanical loading.

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Osteonecrosis

Osteonecrosis of the femoral head may be associated with:

Prolonged systemic corticosteroid use, heavy alcohol use, trauma, radiation exposure, and certain hematologic or systemic diseases.

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Femoral Neck Fracture

Osteoporosis predisposes older adults to femoral neck fractures, some of which are treated with hemiarthroplasty or total hip replacement.

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Genetics

Primary hip osteoarthritis appears to have a familial component.

However, there is no simple Mendelian inheritance pattern.

Multiple genetic and environmental factors probably contribute.

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Pathophysiology

Regardless of the underlying cause, end-stage degenerative hip disease shares several important features.

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Cartilage Degeneration

The articular cartilage progressively loses:

Proteoglycans, normal matrix architecture, and mechanical resilience.

This leads to cartilage thinning, fissuring, and eventual loss.

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Subchondral Bone

As cartilage disappears, the underlying bone is subjected to abnormal loading.

This contributes to:

Subchondral sclerosis, cyst formation, osteophytes, deformity, pain, and progressive limitation of motion.

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Etiology

Primary osteoarthritis remains one of the most common indications for total hip arthroplasty.

Other causes of severe hip destruction include:

Post-traumatic arthritis, osteonecrosis, rheumatoid arthritis, sickle cell disease, recurrent hemarthrosis, Paget disease, ankylosing spondylitis, and other inflammatory arthropathies.

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Developmental Causes

Childhood and adolescent hip disorders can produce secondary osteoarthritis years later.

Examples include:

Slipped capital femoral epiphysis, developmental dysplasia of the hip, and Legg–Calvé–Perthes disease.

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Acute Fracture

Some acute displaced femoral neck fractures, particularly in older adults, may be treated directly with:

Hemiarthroplasty or total hip arthroplasty.

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Associated Conditions

Patients requiring hip replacement often have degenerative disease at other sites, including:

The opposite hip, knees, lumbar spine, shoulders, or other upper-extremity joints.

Coexisting musculoskeletal disease may influence rehabilitation and perceived outcome.

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Diagnosis

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Symptoms of Advanced Hip Arthritis

Pain from hip arthritis is classically felt in the:

Groin, anterior thigh, lateral hip, or knee.

Groin pain is particularly characteristic of intra-articular hip disease.

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Activity-Related Pain

Early symptoms are usually aggravated by:

Walking, standing, stair climbing, and other weight-bearing activity.

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Rest and Night Pain

As arthritis becomes advanced, pain may become present:

At rest, during the night, and with minimal activity.

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Walking Limitation

Severe disease may restrict walking to only a few blocks or even less before the patient must stop because of pain.

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Functional Disability

Patients may report difficulty with activities of daily living such as:

Putting on socks or shoes, dressing, grooming, climbing stairs, getting into a car, rising from a chair, and walking outdoors.

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Range of Motion

Advanced disease commonly causes progressive loss of:

Internal rotation, flexion, extension, and abduction.

Internal rotation is often one of the first movements to become painful and restricted.

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Gait

A painful or weak hip may produce:

Antalgic gait, abductor lurch, shortened stance time, or Trendelenburg gait.

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Indications for Considering Hip Replacement

Typical features include:

Severe pain and functional limitation consistent with physical and radiographic findings, failure of appropriate nonoperative treatment, substantial limitation of walking, and difficulty performing daily activities.

The decision to proceed with surgery is based primarily on the patient’s symptoms and functional impairment rather than radiographic severity alone.

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Physical Examination

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Neurovascular Examination

A complete neurologic and vascular assessment of the affected extremity should be documented before surgery.

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Range of Motion

Hip motion should be recorded, including:

Flexion, extension, internal rotation, external rotation, abduction, and adduction.

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Contractures

Fixed flexion or rotational contractures should be identified because they may affect:

Gait, pelvic position, leg length, and surgical planning.

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Leg-Length Discrepancy

True and apparent leg-length discrepancy should be assessed.

Patients should be informed that perfect equalization of leg length cannot always be achieved because joint stability and soft-tissue tension may take priority.

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Gluteal Strength

Hip abductor strength should be assessed, especially the gluteus medius and minimus.

Preexisting abductor weakness can contribute to postoperative limp.

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Gait Examination

The patient’s gait should be observed for:

Antalgia, Trendelenburg pattern, shortening, stiffness, and use of assistive devices.

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Pain With Motion

Advanced arthritis commonly causes pain at the extremes of hip motion.

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Trendelenburg Test

A positive Trendelenburg sign indicates inadequate hip abductor function or painful hip mechanics.

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Stinchfield Test

A resisted straight-leg raise may reproduce groin or anterior thigh pain from an intra-articular hip disorder.

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Laboratory Evaluation Before Surgery

Preoperative testing is individualized according to patient age, health status, and institutional protocol.

Common studies may include:

Complete blood count, electrolytes and renal function, coagulation testing when indicated, and other targeted laboratory studies.

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Additional Preoperative Testing

An electrocardiogram, chest imaging, or urinalysis may be obtained when clinically appropriate rather than routinely in every patient.

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Blood Management

Routine preoperative autologous blood donation is now uncommon.

Modern blood-management strategies may instead include:

Treatment of preoperative anemia, tranexamic acid, careful surgical hemostasis, and restrictive transfusion protocols.

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Imaging

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Plain Radiographs

Standard evaluation generally includes:

AP pelvis and lateral views of the affected hip.

These studies demonstrate:

Joint-space narrowing, osteophytes, subchondral sclerosis, cyst formation, deformity, and bone loss.

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Additional Views

Standing long-leg or other specialized radiographs may be useful when evaluating:

Limb-length discrepancy, deformity, prior osteotomy, complex anatomy, or alignment concerns.

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Differential Diagnosis

Not all hip-region pain is caused by the hip joint.

Important alternative diagnoses include:

Lumbar spinal stenosis, lumbar disc herniation, radiculopathy, greater trochanteric pain syndrome, occult stress fracture, and neoplasm.

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Neoplasm

Occult malignant disorders that may mimic degenerative hip pain include:

Metastatic bone disease, multiple myeloma, and primary bone or soft-tissue tumors.

Atypical pain, particularly severe night pain or systemic symptoms, should prompt further evaluation.

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Nonoperative Treatment Before Surgery

Total hip replacement is usually considered only after reasonable nonoperative measures have failed or become inadequate.

These may include:

Activity modification, weight reduction, NSAIDs, acetaminophen, physical therapy, walking aids, and selected intra-articular corticosteroid injections.

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Physical Therapy

Physical therapy has important roles both before and after arthroplasty.

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Preoperative Therapy

Prehabilitation may improve:

Strength, gait mechanics, familiarity with assistive devices, and postoperative expectations.

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Postoperative Therapy

Rehabilitation emphasizes:

Walking, transfers, hip and lower-extremity strengthening, progressive mobility, balance, and restoration of independence.

Particular attention is given to the:

Hip abductors, flexors, and extensors.

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Assistive Devices

Patients are taught safe use of:

A walker, crutches, or cane, depending on mobility and postoperative instructions.

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Medication

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Postoperative Analgesia

Pain control is generally multimodal and may include:

Acetaminophen, NSAIDs when appropriate, regional anesthesia techniques, and limited opioid medication for breakthrough pain.

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Venous Thromboembolism Prophylaxis

Patients undergoing total hip arthroplasty require prophylaxis against deep venous thrombosis and pulmonary embolism.

Options may include:

Aspirin, low-molecular-weight heparin, direct oral anticoagulants, or other anticoagulants, depending on individual thrombotic and bleeding risk.

Early mobilization and mechanical compression devices are also important.

Routine use of warfarin for every patient is no longer standard practice.

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Surgery

Total hip arthroplasty replaces both the femoral and acetabular sides of the joint.

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Femoral Component

The femoral head and part of the femoral neck are removed.

A prosthetic stem is inserted into the femoral canal and supports a modular head.

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Acetabular Component

The acetabulum is prepared and typically reconstructed with a metal shell.

A bearing liner, usually highly cross-linked polyethylene or ceramic, is inserted into the shell.

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Fixation

Both femoral and acetabular components may be:

Cemented, uncemented, or combined in a hybrid construct.

Fixation choice depends on:

Bone quality, age, anatomy, fracture pattern, and surgeon preference.

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Surgical Approaches

Several approaches may be used successfully.

No single approach is universally superior for every patient.

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Direct Anterior Approach

The direct anterior approach uses an internervous plane near the interval between the sartorius and tensor fascia lata superficially, with deeper dissection toward the anterior hip capsule.

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Structures at Risk

The lateral femoral cutaneous nerve is particularly susceptible to traction or injury and may produce numbness or dysesthesia over the anterolateral thigh.

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Anterolateral Approach

The Watson-Jones approach uses the interval between the:

Tensor fascia lata and gluteus medius.

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Direct Lateral Approach

In the direct lateral or Hardinge approach, part of the anterior abductor mechanism is elevated from the greater trochanter.

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Potential Concerns

Postoperative abductor weakness and limp may occur if healing is incomplete.

The superior gluteal nerve is vulnerable if the dissection extends too proximally.

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Posterior Approach

The posterior approach splits the gluteus maximus and releases the short external rotators to expose the capsule.

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Sciatic Nerve

The sciatic nerve lies near the operative field and must be protected.

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Dislocation

Historically, the posterior approach was associated with a higher dislocation rate.

Modern repair of the posterior capsule and external rotators, larger femoral heads, improved implant positioning, and contemporary techniques have reduced this difference substantially.

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Bearing Surfaces

The bearing surface is formed by the femoral head articulating against the acetabular liner.

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Ceramic or Metal on Polyethylene

A ceramic or metal femoral head articulating with highly cross-linked polyethylene is one of the most widely used modern combinations.

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Polyethylene Wear

Older conventional polyethylene could produce substantial wear debris, leading to:

Osteolysis and implant loosening.

Highly cross-linked polyethylene has substantially reduced wear.

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Metal-on-Metal Bearings

Metal-on-metal total hip bearings are rarely used in contemporary practice because of problems including:

Metal ion release, adverse local tissue reactions, pseudotumor formation, and high failure rates in some implant designs.

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Ceramic-on-Ceramic Bearings

Ceramic-on-ceramic bearings have very low wear.

Potential concerns include:

Noise or squeaking and rare ceramic fracture, although modern ceramics have markedly improved strength.

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Femoral Head Size

Larger femoral heads can increase:

Jump distance, stability, and impingement-free range of motion.

However, head size must be balanced against liner thickness, component design, and bearing mechanics.

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Minimally Invasive and Rapid-Recovery Techniques

Smaller incisions alone do not necessarily explain faster recovery.

Modern recovery has improved largely because of:

Refined surgical techniques, multimodal analgesia, tranexamic acid, early mobilization, standardized rehabilitation, and enhanced-recovery pathways.

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Follow-Up

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Prognosis

Total hip arthroplasty has excellent long-term outcomes.

Most patients experience:

Major pain relief, substantial improvement in walking ability, increased range of motion, and improved quality of life.

Many return to activities that had previously become impossible because of arthritis.

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Implant Longevity

Older studies demonstrated that approximately 85% of some cemented prostheses remained functional at 20 years.

Modern cemented and uncemented implants can both provide excellent long-term survivorship, with outcome strongly influenced by patient age, activity level, implant design, bearing surface, and surgical technique.

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Complications

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Medical Complications

Potential perioperative medical complications include:

Myocardial infarction, pneumonia, urinary retention, ileus, venous thromboembolism, and, rarely, death.

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Leg-Length Discrepancy

A perceived or true limb-length difference may occur after surgery.

Small discrepancies are often tolerated, but larger differences may cause gait disturbance or dissatisfaction.

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Deep Venous Thrombosis and Pulmonary Embolism

DVT and PE remain important complications, although routine chemical prophylaxis, mechanical compression, and early mobilization have greatly reduced risk.

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Infection

Periprosthetic joint infection is a serious complication that may require:

Antibiotic treatment, surgical debridement, implant exchange, or staged revision surgery.

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Dislocation

Dislocation may occur because of:

Component malposition, soft-tissue insufficiency, impingement, neurologic disease, or high-risk movement.

Risk is generally higher after revision arthroplasty than uncomplicated primary surgery.

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Periprosthetic Fracture

Fractures may occur around the femoral or acetabular components either during surgery or later after trauma.

Treatment depends on implant stability and fracture pattern.

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Heterotopic Ossification

Ectopic bone formation around the hip may restrict motion.

Most cases are mild, but severe cases can cause substantial stiffness.

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Implant Loosening

Components may loosen over time because of:

Wear, osteolysis, inadequate initial fixation, infection, or mechanical failure.

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Osteolysis

Particle-induced bone loss may develop around implants, historically most often from polyethylene wear debris.

Modern bearing surfaces have reduced but not eliminated this problem.

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Nerve Injury

Nerve palsy is uncommon.

The sciatic nerve is most frequently involved, although the femoral, obturator, superior gluteal, or lateral femoral cutaneous nerves may also be affected depending on the surgical approach.

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Revision Surgery

Revision may eventually be necessary because of:

Aseptic loosening, infection, recurrent dislocation, fracture, wear, osteolysis, instability, or component failure.

Revision surgery is generally more complex than primary arthroplasty.

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Patient Monitoring

Long-term clinical and radiographic follow-up is important even in patients who feel well.

Radiographs can detect:

Component migration, polyethylene wear, osteolysis, loosening, fracture, and other asymptomatic changes.

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Follow-Up Interval

Periodic radiographic assessment, often every 1–2 years after the early postoperative period, may be appropriate, with timing individualized according to implant age, symptoms, and surgeon preference.

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Dental Procedures and Antibiotic Prophylaxis

Routine antibiotic prophylaxis before dental procedures is not universally recommended for every patient with a total hip replacement.

The decision should be individualized according to current dental and orthopaedic guidance, especially in patients with:

Previous prosthetic joint infection, major immunocompromise, complex revision arthroplasty, or other specific high-risk circumstances.

Good dental hygiene and prompt treatment of active oral infection remain important.